Automatic telephone system



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AUTOMATI C TELEPHONE SYSTEM JOHN E. OSTLINE" ATT'Y.

J. E. OSTLINE ZQBLBZQ AUTOMATIC TELEPHONE SYSTEM Filed Sept. 6, 1934 1.0 Sheets-Sheet 9 3% E W 3? m M R 3% 0 mm I T o N M0 :3 w E W m N 7 w J W OW k m Q5 vmm .0 0 h 3% L C wlilll ll 02% .2. o L I llllL ONQK o n L w NE Q2. 11 W o? 7 w: A #QM A F@b. fi, W36, J. E. osTuNE I AUTOMATIC TELEPHONE SYSTEM 10 Sheets-Sheet 10 Filed Sept. 6, 1934 E WWW m L m w T r 0 m E V m N H 0 w J 31 J a $1 m mom $5 95 $2352; 03 Ill! 81 Hanna." 3% Ewm U2. mor io "555% hzfiwa 139G ATTY.

Patented Feb. 18, 1936 UNITE STATES PATENT OFFICE AUTOMATIC TELEPHONE SYSTEM Application September 6, 1934, Serial No. 742,887

26 Claims.

This invention relates in general to automatic telephone systems, and the object of the invention, broadly stated, is the provision of new and improved automatic switching and controlling apparatus for use in an automatic telephone exchange.

This invention may be considered as an improvement of the system disclosed in the Wicks patent No. 1,732,186, issued October 15, 1929, wherein uni-directional rotary type switches are controlledby register senders according to the revertive system of control.

Another object of the invention is to provide an improved switch positioning circuit arrangement whereby the stepping speed of the switches need on following calls before a preceding one has been 30 connected with the calling line.

Another feature relates to a repeater, which repeats the revertive control conditions between two exchanges on inter-exchange calls.

The invention, its features and operation will be described in detail in the following specification with the aid of the accompanying drawings comprising Figs. 1 to 10, inclusive. Fig. 1 discloses a so-called one-line diagram showing the trunking system for two Sim-line groups. Fig. 1a shows the manner in which Figs. 2 to 10, inclusive, are to be arranged with the corresponding lines in alignment. Figs. 2 to 10, inclusive, show' by means of the usual circuit diagram the'new and improved selector, connector, combination call controller and sufiicient of the associated apparatus to render possiblea thorough understanding of the invention.

Referring now to the upper portion of Fig. 1, the subscribers lines are divided into groups of five hundred lines and these groups are again divided into groups of one hundred lines. The squares designated I09 shown in the upper lefthand corner represent each 100 line circuits which are connected to the banks of the primary line finders, there being ten primary line finders for each one hundred line circuits. The primary line finders terminate in primary trunks which are multipled in the banks of the secondary line finders and in the banks of the group finders associated with the call controllers. The secondary line finders terminate in secondary trunk relay groups and in first group selectors. There are as many secondary line finders and secondary trunk relay groups as is needed to take care of the trafiic originating in this 500 line group. The banks of the first group selectors extend to second group selectors and are multipled in the manner illustrated. The second group selectors have access to connectors and the connectors in turn have access to the line circuits of the subscribers lines in the usual manner. Each 100 group of subscribers lines has a start lead extending to a start relay associated with the allotter. The allotter has access to as many combination call controllers as is required for the traffic in this sub-group of lines. As previously stated, the group finder of each call controller is multipled to the primary trunks, while a secondary trunk finder associated with each call controller is used for selecting an idle secondary trunk relay group. The combination call controller has a number of relays and switches which will be described more fully in connection with the remaining figures. The lower portion of Fig. 1 shows the second or last 500 line group whichis similar to the upper portion and is shown in order to show the usual trunking connections between the first and second selectors.

In Fig. 2 the circle at the extreme left indicates subscriber A, whose number in this case is 1121. The line conductors I and 2 extend from the telephone to the line circuit comprising relays I and 20. Conductors I, 2 and 3 are the connector normals and extend by way of cable 4 to the connector bank shown in Fig. 5. Conductors 6 and I are the start conductors for marking the calling group and for initiating the operation. The calling end of the line circuit terminates in the banks of the primary line finder. Mechanically, the switch mechanism of the primary line finder is similar to the switch mechanism of the well-known rotary line switch, except that it has been provided with two sets of single ended multiply connected wipers mounted on the same shaft, wipers IOI, I03, I05 and I01 being one set, and wipers I02, I04, I06 and I08 being the other set. A separate set of banks is provided for each set of wipers, the two setsof banks being placed side by side. These two sets of wipers are positioned on the shaft 180 degrees apart so that when one set of wipers is moved off the last set of contacts on its associated set of banks, the other set of wipers is moved on to the first set of contacts in its associated set of banks. Since each bank shown has a capacity of 50 lines the primary finder therefore has access to subscribers lines. In this case each primary line finder comprises only the wipers and banks and the motor magnets for controlling the operation of the finder.

The primary line finders terminate in the primary trunks which terminate in the banks of secondary line finders and in the banks of the group finders associated with the combination call controllers. The secondary line finder shown in Fig. 2 comprises a 50-point switch similar in the mechanical construction and operation to the well known rotary line switch. Each secondary line finder terminates in a secondary trunk relay group which is shown in Fig. 3.

The secondary trunk relay group shown in Fig. 3 comprises relays for feeding talking battery to the calling and called subscribers and for maintaining the connection after the combination call controller is released. In the bottom portion of Fig. 3 is shown the wipers of the secondary trunk finder associated with the particular combination call controller shown in Figs. 6, 7, 8 and 9. Each secondary trunk relay group is connected to a first group selector such as shown in Fig. 4. The first group selector shown in Fig. 4 comprises a number of relays and a motor magnet for operating the wipers of the selector over its bank contacts. The wipers and banks are arranged mechanically similar to the wipers and banks of the primary line finder and in this case the first group selector wipers have access to one hundred second group selectors indicated by the rectangle. In addition the bank contacts are divided up into groups of ten contacts each and are numbered in the manner diagrammatically illustrated for the bank contacts accessible to wipers 3H and 342. The wipers of the first selector are always returned to their normal position in which position the off normal springs 3 l 5 and 3 l 6 are opened as illustrated. One of the trunks, accessible in the fourth group of bank contacts of the first selector and in the fourth group of bank contacts of the other similar first selectors, is shown comprising conductors 352, 356 and 358, terminating in the second group selector shown by the rectangles in Fig. 4. The second group selector is identical in circuit operation and in mechanical construction to the first selector shown. The banks of this second selector as well as the banks of similar second selectors are connected to a number of groups of connector switches in the well known manner.

The connector shown in Fig. 5 is accessible to the fifth group of trunks in the second selectors. The connectors are mechanically similar to the group selectors and each comprise six relays and a motor magnet for controlling the operation of the connector wipers. The wipers of the connector have access to one hundred lines and are restored to normal upon the release of the connection. The banks of the connector are likewise divided into ten groups of lines and the lines terminate in the connector banks in these groups in the manner indicated by the numbering associated with the banks accessible to wipers 4H and 412, To the right of the connector in Fig. 5 is shown the line circuit, the primary line finder banks and the subscribers telephone station B.

A number of two-step relays have been shown in the selector and connector switches which relays upon energizing in their first step operate only the armatures designated by roman numerals I, while in their second step the armatures designed by the roman numerals II are operated.

At the extreme left of Fig. 6 is shown the allotter and associated start relays 3| and 4| for two of the one hundred line groups, it being understood that a relay, such as 3! or 4|, is provided for each hundred line group. The start conductors 6 and 6 each extend from a hundred line group to wiper 33 of the allotter. The allotter has access to as many combination call controllers as are needed to take care of the trafiic originating in this five hundred line group. The upper portion of Fig. 6 shows the wipers of the group finder associated with the particular combination call controller shown in Figs. '7, 8 and 9. As shown, the wipers of the group finders have access to primary trunks such as the one shown in Fig. 2. The marking conductors 1 and 1 extend through start relays, such as relays 3| and 4 l, and are connected to multipled bank contacts accessible to wipers 6! l in the group finder to mark the calling group. The mechanical construction and operation of the group finder is similar to the mechanical construction and operation of the well known rotary line switch. Both the group finder and the secondary trunk finder are part of the combination call controller shown in Figs. 7, 8 and 9.

In Fig. '7 are shown a number of the relays of one of the combination call controllers. Relay Mil in Fig. '7 has a weighted armature HI with a weight 142 on its right-hand end, which starts vibrating between contacts 143 and 144 when the armature is released. The relays shown in Fig. 8 are also part of this combination call controller. In the extreme right of Fig. 8 is shown the counting switch CS which is mechanically similar to an eleven point rotary line switch in which the wipers are restored to normal position and in which the wipers are advanced one step upon each energization of the motor magnet 885. In Fig. 9 is shown the sending control switch X comprising wipers 9 l3 to 9|5, inclusive, the motor magnet 9 H) which advances the wipers one step upon each deenergization and the off-normal springs 9| 2 for controlling the restoration of the wipers after the sending operation. The sending control switch X is m chanically similar to the counting switch CD. The sequence switch SS and the four register switches RA, RB, RC and RD are mechanically similar to the well known rotary line switch, but in this case the wipers of the respective switches are operated one step upon each energization of its associated motor magnet. Each of these latter switches have off normal springs for controlling the restoration of the switch wipers after the sending operation.

Fig. 10 discloses a make busy relay 500 located in a distant ofiice and two trunk conductors 505 and 50'! extending to the local exchange wherein the line conductors terminate in the repeating coil R3, and an incoming repeater comprising a plurality of relays. Relays 5H] and 520 are polarized relays which operate only when current is sent through their windings in the proper directions. The incoming repeaters terminate in second group selectors which have access to the connector switches in the manner illustrated in Fig. 4.

General operation For the purpose of this description it has been assumed that the subscribers lines are arranged in groups of five-hundred lines, that each one hundred line group has ten primary line finders, and that these primary line finders are concentrated through the second line finders into a group of thirty secondary trunks. Each primary trunk comprises a primary line finder for finding the calling line and this trunk terminates in the secondary finder banks for the purpose of establishing the final connection. Each primary trunk is also multipled to the banks of the group finders for the purpose of associating a combination call controller with a calling line. Each secondary trunk consists of a fifty-point secondary line finder for finding primary trunks and associated with each secondary trunk is also a group of secondary trunk relays for holding the connection, for controlling the metering and feeding talking battery to both calling and called subscribers. These secondary trunk relay groups terminate in first group selectors.

When a subscriber initiates a call the line relay in his line circuit operates in the usual manner to initiate the operation of an idle call controller through the allotter and to mark the calling group in the bank of the group finder of the selected controller and to mark the calling line in the banks of the primary finders. The group finder associated with the allotted controller will first of all find a free primary trunk within the particular sub-group of one hundred lines where the call originated. As soon as this operation has taken place, the primary finder associated with the selected primary trunk will start hunting for the calling line. As soon as the calling subscribers line has been found the subscribers cut-off relay operates and the connection is switched through to the controller.

It will beapparent from the foregoing description that for each call originated, two selecting motions are required to find the calling line. Owing to the fact that call controllers may serve a maximum of five one hundred line sub-groups, it may appear possible that long waits for the dial tone will result when calls are started simultaneously in different sub-groups. This is prevented by the following arrangement. If, for instance, calls are originated in three sub-groups at practically the same instant, the first controller taken into use will find, via its group finder, the sub-group in which the call has originated, at this point, and before the calling subscribers line has actually been found, a second call controller will be started by the advance of the allotter to take care of the second call, and so on. In other words, each succeeding call, if in a difierent sub-group, need not wait for the complete selection of the calling subscribers line, but only long enough for an allotted call controller to find a free trunk within a sub-group where the call has started.

As soon as the calling subscriber is connected 1 with the controller, dial tone is placed on the line indicating that dialling of the desired num ber can now take place. The dial pulses are then stored in the call controller on the regisfound, it is held in readiness by the call controller to receive the transmission of a call as fast as the subscribers dial pulses are stored on the register switches. Immediately after the seizure of the primary trunk by the group finder and the secondary trunk by the trunk finder, a local circuit is set in motion whereby the secondary line finder associated with the secondary trunk seized is stepped to the primary trunk over which the call is being dialled in by the calling subscriber. This connection between the primary and the secondary trunk is made entirely independent of all other functions taking place at the same time and does not require any relays or equipment, other than that contained in the call controller, for its completion. After the secondary line finder has been associated with the proper primary trunk, the circuit between it and the secondary trunk remains open.

Instead of sending stepping impulses to the selectors and connectors to place their wipers in front of a desired group, the seizure of a selector or connector will cause it to step by self-interruption to the beginning of the first trunk group in the case of a group selector or to the first tens group in the case of a connector. At this point a signal is sent to the call controller by a charge of current strength. This change produces a momentary release and reoperation of the line relay in the selector and the same process is repeated until the wipers stand at the beginning of the desired group; the desired group being determined by the position of the register switches in the controller. With this kind of stepping operation the stepping speed of the switch need not be within any particular limits because the controller will always wait until the proper position has been reached. Assuming that the line called is available, the connector switch will signal this fact to the call controller as soon as a connection has been established. At this instant, a call controller and its associated group finder and trunk finder release from the connection and a talking circuit is established from the subscribers line by way of the primary line finder, the secondary line finder, the secondary trunk relay group, its associated first group selector, and selected second selector and connector.

In case one of the selectors encounters a busy or in case the called line is busy, the entire connection, including the first selector and second selector, is instantly released and made available for other calls, and busy tone is transmitted from the call controller to the calling subscriber.

Having given a general description and operation of the system a detailed description will now be given. For this purpose it will be assumed that subscriber A initiates a call and in response to the removal of his receiver the following circuit for line relay H) is completed; from grounded armature 23, conductor 2. substation loop, conductor l, armature 2! and through the winding of line relay H! to grounded battery. At armature ll relay Ill disconnects the Winding of cut-off relay 2E! from the connector normal conductor 3 and connects battery through the winding of relay 2!! by way of conductor 5 to the bank contacts in the primary line finders to mark the calling line. At armature l2 relay ll] grounds conductor E to complete a circuit for vibrating relay M0 in the controller as follows: from grounded armature l2, conductor 6, armature 32, wiper 33' of the allotter which has preselected this idle call controller, conductor 628, armature H5 and through the upper winding of relay 140 to battery. At armature l3 relay ill marks the calling group in the banks of the group finders associated with the call controllers by marking as many multiple bank contacts accessible to wipers, such as wiper 6, as there are primary finders in this calling one hundred line group. This group marking enables the group finders to locate the particular hundred line group which is calling. Relay 146 operates its weighted armature 14! to close contacts 143, thereby completing a circuit for energizing slow to release relay 750 by way of armature I62. Relay 159, upon energizing, at armature 15I connects the test Wiper 215 of the secondary trunk finder to the upper winding of the secondary trunk finder test relay at armature I52 closes a self interrupting circuit by way of armature 133 and conductor 288 to the motor magnet 296 of the secondary trunk finder; at armature T53 prepares a point in the circuit for c0nnecting dial tone to the calling line, at armature l54 prepares a holding circuit for relay 710; at armature T55 completes a locking circuit for itself independent of armature 162; at armature 156 completes an energizing circuit for slow to operate relay E20; and at armature I51 prepares a stepping circuit for sending control switch X. Motor magnet 29!] of the secondary trunk finder energizes over the above traced circuit and at its interrupter springs 289 interrupts its own circuit whereupon the motor magnet deenergizes and advances the wipers one step for each deenergization. The motor magnet 29?; interrupts in a buzzer-like manner to advance the wipers of the secondary trunk finder step by step until test wiper 215 engages an idle trunk having negative battery potential on the bank contact encountered by wiper 215. When test wiper 215 encounters an idle trunk test relay 7T6 energizes over the following circuit: from ground through the upper winding of test relay Tlil, armature 15!, conductor 285, test wiper 215, control conductor 256, and through the upper windings of relays 320 and 330 in the first group selector to grounded battery. Test relay T19 alone energizes over this circuit and at armature 'l'H prepares a circuit for grounding the negative conductor 252 or the positive conductor 268, dependent upon the operated condition of relay 8H]. At armature 112 relay 710 prepares a circuit for connecting grounded battery through the winding of relay 830 to the negative conductor 252 or positive conductor 258, dependent upon the operated condition of relay 8l0. At armature I13 relay 1?!) immediately opens the circuit of motor magnet 29!) to cause the wipers of the secondary trunk finders to stop on the idle trunk selected; at armature 114 prepares a point in the circuit for release relay 210 in the secondary trunk relay group; at armature 115 connects up the spark quenching condenser and the resistance Tl!) to motor magnet H'il of the secondary line finder; at armature 7T6 prepares a circuit for energizing the A. C. relay 190; at armature Ti! prepares a circuit for relay 789 which is short circuited from ground at armature 19 I; and at armature 118 short circuits the upper winding of test relay 110 to connect direct ground to conductor 256 by way of armature I I conductor 285, and wiper 215 to energize the two-step relay 320 in the first group selector in its first step to operate only armature 324. Relay 330 being marginal will not energize over its upper winding in parallel with the upper winding of relay 320. Relay 32!] operates only its armature 324 to open the restoring circuit of the first group selector.

Slow to operate relay I20 energizes over the following circuit: from grounded wiper 9|3 of the sending control switch in engagement with its first or normal position bank contact, conductor I92, armature 756 and through the winding of relay 120 to battery. At armature 'l2l relay I20 closes a self interrupting circuit to the motor magnet 618 of the group finder by way of armature HI and conductor 620; at armature 122 completes the holding circuit through the lower winding of test relay H0 and completes holding circuits for relays 100 and H0 through their upper windings, but these latter relays, being marginal, do not energize at this time over their upper windings; at armature 123 prepares a point in the circuit of the group finder test relay H0 and at armature I24 closes a circuit for shunting the lower winding of group finder test relay H0 when the group finder test wiper 614 encounters a busy primary trunk. Whenever Wiper 6! 4 engages a grounded bank contact indicating a busy primary trunk, a circuit for shunting the lower winding of group finder test relay H3 may be traced as follows: from the grounded bank contact engaged by wiper 514, conductor 624, armature H2 and resting contact, armatures 124 and 123, lower winding of group finder test relay HI! and by Way of resting contact and armature 105 to ground. When the group test wiper Bil of the group finder encounters one of the multiple connected bank contacts having group calling battery potential connected thereto at the time the primary test wiper 6l4 does not encounter a grounded bank contact a circuit may be traced for energizing the group finder test relay 'HD as follows: from ground by way of armature 105 and resting contact, lower winding of group finder test relay H9, armature 723, conductor 62'], group test wiper G! I, through one of the multipled bank contacts through the winding of'relay 3|, common start conductor 1 for this hundred line group, armature l3 and by way of the resistance to grounded battery. Relay 3| energizes in series with group test relay HQ, and at armature 32 disconnects start ground from wiper 33 in case no other line is calling. Group test relay H0, upon energizing in series with relay 3| when the calling group is found, at armature Ill opens the circuit to motor magnet 6l8 to stop the wipers of the group finder on the bank contacts terminating an idle primary trunk; at armature H 2 and resting contact opens the shunt circuit through the lower winding of relay H0, and at its working contact prepares the test circuit to the line test relay 100 which will operate when the selected primary ine finder finds the calling line. At armature H3 relay H6 grounds conductor 625 by way of armature 166 to complete a circuit for operating the motor magnet N8 of the selected primary line finder; at armature H4 closes a common spark quenching circuit for the connected motor magnet of the primary line finder; at armature H5 opens the circuit to the upper winding of relay 140, and at armature H6 grounds conductor 629 to energize motor magnet 35 of the allotter to cause the wipers of the allotter to be stepped in search of an idle combination call controller which will be used on a subsequent call. The circuit for operating the allotter magnet 35 extends by way of grounded conductor 629, bank contacts engaged by wiper 34, interrupter springs 36 and through the winding of motor magnet 35 to battery. Motor magnet 35 operates in the manner of a buzzer as long as wiper 34 engages Cit e oarszo springs II9i until such time as line test relay I60 energizes. and opens the circuit. thereto at armature I66. During the stepping operating. of motor magnet; IIS the common spark quenching circuit is completed by way of conductors I26 and 62.6 to the condenser H6 and resistance III to ground at armature: I ItII Relay I40 deenergizes. when its circuit is openedat armature 1 I 5 or by the operation of the allotter, and upon deenergizing. releases its armature IIII thereby causing the weight: 1.42 thereon to vibrate between springs M3 and IM: for a: predetermined period. Each time armature I I'I engages springs I43 or 1 44' the circuit through slow to release relay 150 is again completed to" maintain this relay energized. The: weight 1 42' on armature springs MI may be adjusted. so that this spring may vibratefor a variable number of seconds before it finally comes to rest between the two springs T43 and T44. In the instant disclosure it is assumed that the weighted armature I4 I will vibrate for a period of approximately four seconds and therefore hold relay 150 energized during that period. Relay I50 in the normal. operation of the system, however, should not deenergize unlesssomefault occurs or unless the calling subscriberfails todiat within the required period. Thetes-t conductors ofbusy subscribers lines are grounded and therefore when the test wiper I65 or I06 of the primary line finder encounters a grounded bank contact terminating a busy line, a circuit may be completed over conductor H5, wiper 6I4, conductor 624, armature I I2 and working contact and through the lower winding'of l-ine test relay to ground for short relayIIIB. Line test relay Illll being short circuited will not energize over this circuit. When a calling line is found,

test wiper I05 or I06-will encounter acalling battery potential extending through the winding of cut-ofi relay 20 and armature 22 in parallel for energizing line test relay I-I'IDover the previously traced circuit. Line test relay 100, upon energizing, at armature NH grounds conductor 28| to closea self interrupting circuit to the motor magnet I6I of the secondary line finder; at armature I62 connects up'a circuit to the secondary winding of transformer T inseries with the A. C. relay 1-90; at armatures I63 and I04 completes a circuit including the calling subscribers loop for energizing line relay I30; at armature I65 grounds conductors 624 and H5 to operate the cut-off relay 2'0, and to mark the primary trunk busy, and at armature I66 opens the circuit to motor magnet I I8 to stop the wipers of the primary line finder on the bank contacts terminating the calling line. Cut-off relay 20, upon energizing, at armatures- 2I- and 23- disconnect the line relay II) and ground from the line conductors I and 2, at armature 22 disconnects battery at its resting contact and at its working contact completes a looking circuit for itself from conductor 5 now grounded over'conductor II5. Line relay Ill-deenergizes and at armature l I busies the called test conductor 3 by connecting ground thereto byway of grounded conductor H5, wiper I05, conductor 5., working contactandarmature 22, armature' III: and resting contact, to conductor 3. At armature I2. relay I6 removes ground from conductor 6 toremove the start. ground condition and at armature.- I13- disconnects. group marking battery from; conductor I and relay 3.1, The circuit for relay 3|, was. opened at armature H15 in response tothe operation of the. test relay' I00. In; addition. the operation of relay Hill at armature Hi5 opens the original energizing circuit of group test relay Hi: and also at the working. contact of springs I165 short circuits the lower winding of relay 180' but both these relays, I66 and I III, are newmaintai'ned; energized solely over their'upper winding-s from; groundedarmature I22.

A circuit: for energizing line relay I36 in the call. controller may be traced as follows: from ground through. the lower winding of relay I36, armatureIIIlLco-nductor 62-3, wiper 6 I 5, conductor ti-t, wiper IIIl'Ia, conductor 2, through the call-ing substation loop of subscriber A, conductor I, wiper H11, conductor: I IIJ,. wiper. 6:-I 6, conductor 622, armature: I033. and through the upper winding of line: relayI-(ill to groundedbattery. At armature- 731 line relay I30 completes an: obvious circuit for energizing: to release relay I60. At armature 1-6.1 relay I6ll connects dial tone to the calling subscribers line as follows: from dial tone source (Fig 9 by way of. 01? normal springs 933,. conductor I89, working. contact and armature I53, armature I61, tone condenser TC, armature I03, conductor 622;. wiper 6I6-,- conductor I I I,. wiper IItI", conductor I, to the: calling substation loop. At armature 162i relay I60- opens the original energizing: circuit of. relay 156, but this relay is maintained: in: operated positionthrough its own armature 155;. at armature 163 closes a shunt around: armature 1.56 to maintain release relay IE-0' in energized; position; at armature I64 complates; a circuit front grounded armature 81 and conductor I93 through the lower winding ofrelay M6; to: grounded. battery to: again energize relay no inorder' to maintain slow to release relay I50 inaenergized; position. At: armature I65-relayI6l] completes acircuit. for energizing relay 8-10 as follows: from ground. by way of armature I65, conductor.- I843. andthro-ugh; the winding of relay 816 to: grounded battery; At armature I66 relay I60 completes a circuit for energizing motor magnet 92E] of the sequenceswitch ss as followsi from. ground by way of. armature: I66, conductor I93, armature Q61, and through the winding of motor magnet 9211 to" grounded battery. Motor magnet 920: energizes over: the above tracedcircuit andhsteps Wiper 923 in engagement with its first: bank. contact, and. operates itsinterrupter spring'ili I- 0ft" normal springs 922' of the switch SS: close; in response to wiper 92 3- engaging the first bank contact.

. Relay are, uporr energizing, at armature BTI' connects; an C'.- source through the primary winding. of" transformer T by way of conductors- I 8 I' and I88 At armature 812' relay 810 opens a point in the self restoring circuit of counting switch: CS; at armature 813 prepares a circuit for relay 820, at" armature 8-I4- prepares .a point in the locking circuit of relay 840 and at armaing contact and armature I82, armature III, armature IOI, conductor 28I, wiper ZII, conductor I 64, interrupter springs I 62 and through the winding of motor magnet IGI to grounded battery. Motor magnet I 6| operates in the manner of a buzzer to advance the wipers of the secondary line finder step by step until wiper I59 finds the conductor marked by the group finder .associated with the call controller in use. The conductor marked by the group finder corresponds to the primary trunk taken into use and in this case is the conductor I22, and therefore when wiper I59 engages the bank contact terminating conductor I22 a circuit is completed for A. C. relay I90 as follows: from the righthand terminal of A. C. relay I90 through the secondary winding of transformer T, conductor 283, wiper 213, conductor I60, wiper I59, conductor I22, wiper 6II of the group finder, conductor 62I, armatures I02, 116 and I8I to the left-hand terminal of A. C. relay I90. Since the circuit to the primary winding of transformer T has previously been closed by the operation of armature 8II, A. C. relay 190 is energized over the above traced circuit. At armature I9I relay !90 opens the stepping circuit to motor magnet IGI and stops the secondary line finder in engagement with the primary trunk taken into use by the group finder and also removed a ground shunt from the winding of relay 180 which now operates from battery through the winding of motor magnet I6I. Due to the high resistance winding of relay I80 motor magnet I 6| does not operate in series therewith with the result that the wipers of the secondary line finder stop in engagement with the selected primary trunk. At armature I8I relay I80 opens the circuit of A. C. relay I90 which now deenergizes and at armature 182 looks itself independent of armature III in case relay 110 should deenergize.

A brief review will now be given of the operations which have resulted from the initiation of a call prior to the calling subscriber dialling the desired called subscriber's number. 1) The allotter has assigned an available call controller. (2) The controller has placed its associated group finder on an available primary trunk to the calling hundreds group. (3) The controller at this time steps the allotter forward so that another call controller may be started if there are other calls waiting. (4) The call controller steps the primary line finder associated with the primary trunk selected to the calling line. (5) The secondary trunk finder associated with the controller in use has selected a free secondary trunk and with it a first selector. (6) The call controller has stepped the secondary line finder associated with the selected secondary trunk relay group to a position where it can connect with the primary line finder already selected by the controller. This placing of the secondary line switch in association with the primary line finder does not establish any circuit connection.

(7) The calling subscribers dial telephone is now connected with the controller and the controller is connected with the first selector. The equipment between the first selector and the primary line finder, that is, the secondary line finder and the secondary trunk relay group, permanently associated with the secondary trunk, are held in readiness for the completion of the connection, but are not as yet in the circuit nor do they perform any function in the setting up of the connection.

The calling subscriber may now dial the digits corresponding to the called subscribers telephone number and in this case we will assume that the caling subscriber dials the digits 4-5-6--'I. In response to the first digit or digit 4 line relay I30 deenergizes four times and each time transmits .a ground pulse by way of armature I32 over conductor I91, through the Winding of relay 900, Wiper 923 in engagement with its first blank contact, and through the winding of motor magnet 930 of the first digit storing switch or register switch RA to grounded battery. Storing or register switch RA being of the direct drive type steps its wiper 934 one step in response to each energization of motor magnet 930 and since four ground pulses are transmitted thereto by way of armatures I66 and I32, wiper 934 will come to rest in engagement with its fourth bank contact terminating the No. 4 conductor included in cable 090. In response to the first step of wiper 934 off normal springs 933 disconnects dial tone from the calling line and also operates the off normal springs 932 to prepare the restoring circuit for switch RA, which, however, is open at this time at armature 8II. Relay 900 energizes in series with motor magnet 930 and due to its slow release characteristics maintains its armature 90I operated for the duration of the impulses in each digit. At armature 90I relay 900 therefore opens the circuit to motor magnet 920 which accordingly deenergizes. At the end of the first digit slow to release relay 900 deenergizes and again completes the circuit for energizing motor magnet 920 to again cause the sequence switch wiper 923 to step into engagement with its second bank contact to prepare the second register or storing switch RB for the second digit.

In response to the calling subscriber dialling the second digit, or digit 5, line relay 130 deenergizes five times and in response to these deenergizations completes the following circuit: from ground by way of armature 16b, armature I32, conductor 191, through the winding of slow to release relay 909, wiper 932 in engagement with its second bank contact and through the winding of motor magnet 940 of the second register or storing switch RB to negative battery. Motor magnet 940 operates five times and sets the Wiper 944 into engagement with its fifth contact terminating the No. 5 conductor in cable 890. In response to the first step of wiper 944 off normal springs 943 completes a circuit for energizing relay 820 in order to retransmit the first digit stored to the first group selector, and at the off normal springs 942 prepares the restoring circuit for switch RB. Slow to release relay 900 operates in the same manner as before to open the circuit to motor magnet 929 and shortly after the second digit relay 989 deenergizes to again complete the circuit for operating motor magnet 920 to step its associated wiper 923 into engagement with its third bank contact in readiness to register the third digit.

In response to the calling subscriber dialling the third digit, or digit 6, line relay ISO is deenergized six times and each time transmits a ground impulse through relay 9% and wiper 923 through the winding of motor magnet 950 to battery. Motor magnet 950 in a similar manner steps its wipers 954 into engagement with its sixth bank contact terminating the No. 6 conductor in cable 890. In response to the first step of Wiper 954 off normal springs 952 close a point in the restoring circuit for register RC. Off normal springs 953 also close on the first step of wiper 354' to prepare a circuit for relay 820 in order that the call controller will retransmit the second digit stored at a time when the third digit is being registered. Relay 388 and magnet 928 energize and deenergize in the manner previously described to step the wiper 923 after the third digit into engagement with its fourth bank contact in order to register the fourth digit.

In response to the calling subscriber dialling the fourth digit, or digit 7, line relay 130 deen ergizes seven times and on each deenergization transmits a ground pulse through relay 933 and motor magnet 388 of switch RD to grounded battery. Motor magnet 93!] advances wiper 964 one step in response to each energization to step wiper 954 into engagement with its seventh bank contact terminating the No. 7 conductor in cable 898. In response to the first step of wiper 984 off normal springs 962 close a point in the self-restoring circuit of switch-RD and also closes oil normal springs 963 so as to cause the controller to retransmit the stored third and fourth digits. After the fourth digit, relay 933 deenergizes and at armature 90! again completes the circuit for energizing magnet 328 to step wiper 923 into engagement with its sixth bank contact. The called number has now been stored on the storing switches RA, RB, RC and RD.

As soon as wiper 943 takes its first step in response to the second digit dialled by the calling subscriber. off normal springs 343 close a circuit for energizing relay 828 to start the group finding cycle of operations of the controller. The operation of off normal springs 943 completes a circuit for energizing relay 829 as follows: from ground by way of off normal springs 943, first bank contact engaged by wiper N of the sending control switch X, conductor 853, armatures 813 and 3M, and through the winding of relay 828 to grounded battery. Relay 823, upon energizing, at armature SZl completes a circuit for energizing slow to release relay 858 as follows: from ground by way of armatures M3 and 83l, first bank contact and wiper 885 of counting switch CS and through the winding of relay 853 to grounded battery. At armature 822 relay 828 completes a circuit from grounded armature M3 for energizing the motor magnet 835 of counting switch CS which upon energization positions its pawl preparatory to stepping the wipers 88B and 83? since the counting switch is of the indirect drive type, At armature 823 relay 823 prepares a locking circuit for itself and at armature 824 connects grounded battery through the winding of relay 836 to negative trunk conductor 252 to energize the line relay 3% in the first group selector as follows: from ground by way of resting contact and armature 32 i in Fig. 4, through the lower high resistance winding of line relay 3E3, armature through the upper low resistance winding of line relay 3H3, resting contact and armature 33!, conductor 252, wiper 2", conductor 281', armature 8H and its resting contact, conductor I34, armature H2, conductor I85, armature 324 and through the winding of marginal relay 838 to grounded battery. Due to the high resistance of the lower winding of line relay 3m marginal relay 833 will not energize over the above traced circuit.

Relay 3%, upon energizing, at armature 85! prepares a circuit for locking slow to release relay 838 and at armature 852 completes a circuit for energizing motor magnet 3H1 of the sending control switch X by way of conductor 83 i.

Motor magnet 9m, upon energizing, positions its pawl preparatory to stepping the wipers of the sending control switch and at interrupter springs 9 opens a point in its restoring circuit. Sender control switch X, like counting switch CS as previously stated, is of the indirect drive type in which the wipers are only stepped upon deenergization of the associated motor magnet.

In the first group selector shown in Fig. 4 line relay 3"], upon energizing over the previously traced circuit, at armature 3l2 completes a circuit for automatically advancing the wipers of the selector as follows: from ground by way of armature 3l2, interrupter contact 339 and resting contact, armature 333 and through the winding of motor magnet 338 to grounded battery. Motor magnet 338 positions its pawl preparatory to stepping the wipers of the selector and at its interrupter contacts 339 interrupts the previously traced circuit via motor magnet 338 to cause its deenergization in case wipers 345 or 346 are not in engagement with a grounded group contact. In this case since wiper 345- is normally in engagement with a grounded group bank contact the circuit is completed from this grounded bank contact by way of wiper 345 and armatures 313 and 333 through the winding of motor magnet 333 to maintain the magnet in energized position. A circuit may now be traced for short circuiting the lower high resistance winding of line relay 3E8 as follows: from ground by way of armature 312, interrupter contacts 339 and its working contact, lower high resistance Winding of relay 3H], armature 32! and its resting contact to ground. Since the high resistance winding of the relay 3l0 is short oircuited marginal relay 838 in the call controller is energized in series with the lower winding of line relay 3H3. The operation just described, that is, the change of resistance in the circuit extending to relay 838, occurs each time a grounded group contact is encountered by wipers 345 or 346. Since the grounded bank contact accessible to wipers 345 and 346 designate the different trunk groups as previously described, then this change of resistance in the circuit to the call controller takes place at the start of each trunk group. Marginal relay 838, upon energizing in series with the low resistance winding of line relay 3H3, at armature 83| completes an obvious circuit for energizing relay 840, and at armature 832 prepares a locking circuit for relay BID. Relay 848, upon energizing, at armature 84! opens the circuit of relay 828 which accordingly deenergizes, and at armature 842 completes a locking circuit for itself from grounded armature 874. Relay 828 deenergizes and at armature 82! momentarily opens the circuit of relay 853 and at armature 322 opens a circuit to the motor magnet 885 of counting switch US to deenergize the motor magnet to step the wipers of the counting switch 886 and 88'! into engagement with their first bank contacts. In this position slow to release relay 853 is maintained energized from the grounded multiply connected bank contacts engaged by wiper 885 of counting switch CS in the second and subsequent positions. At armature 824 relay 828 opens the circuit through line relay 3H3 in the group selector and to the marginal relay 830 in the call controller, and at armature 825 completes a short circuit around the winding of relay 840 to cause its deenergization. This short circuit may be traced as follows: from the left-hand terminal of relay 848, armature 825, armature 842, to the right-hand terminal of relay 343.

In the first group selector the deenergization of line relay 318 at armature 312 opens the short circuit around the high resistance winding of line relay 318 and at armature 313 opens the circuit maintaining the motor magnet 338 in energized position. The magnet 338 accordingly deenergizes and steps the wipers of the group selector intoengagement with the first bank contact in the first group.

In the call controller the deenergization of relay 838 at armature 881 opens the circuit extending to relay 848. Relay 848 is slow to deenergize since its winding is short circuited at armature 825, and upon fully restoring at armature 841 again completes the circuit for energizing relay 828. Relay 828 again energizes and at armature 822 again completes the circuit extending to the motor magnet 885 of the counting switch CS and at armature 824 again connects battery to the winding of marginal relay 838 through both the high and low resistance windings of line relay 318 to again energize the latter relay.

Line relay 3 1 8, upon energizing, at armature 312 closes a self-interrupting circuit through motor magnet 333 to automatically advance the wipers of the selector over the contacts in this first group. The closure of armature 313 is effective at this time because wiper 345 does not encounter a grounded group bank contact until the last line in this group is reached. During the self-interrupting operation of motor magnet 338 the make contacts of interrupter spring 339 are not closed for a sufiicient time to effectively short the high resistance winding of line relay 318 and therefore during this operation relay 838 does not operate. Motor magnet 338, upon each deenergization, continues to advance the wipers cf the selector step by step until the wiper 345 engages a grounded group contact, in this case the last trunk in the first group, at which time motor magnet 338 is maintained energized from the grounded group contact by way of wiper 345 and armatures 313 and 333 as previously described. At armature 312 and interrupter springs 339 and its working contact the lower high resistance winding of line relay 318 is again shorted to change the resistance in the circuit extending to relay 838 in the call controller to cause relay 838 to again energize and operate the relays in the call controller in the same cycle of operations as previously described. That is, relay 830 energizes and causes the energization of relay 848, as previously described. Relay 848 energizes and causes the release of relay 328. Relay 348, upon deenergizing, causes the counting switch CS to take another step and opens the circuit to relays 318 and 838. The deenergization of line relay 318 in the group selector steps the wipers of the selector to the first contact in the second group. Relays 838 and 848 deenergize and relay 828 reenergizes as before. Relay 828, upon reenergizing, again completes the circuit for energizing line relay 318 by way of armature 824 to again cause the automatic stepping of the wipers of the selector to the last trunk in the second group. From the foregoing it will be seen that at this time group wiper 345 engages a bank contact designating another group, the resistance of the circuit between the call controller and the selector is changed to cause the cycle of relay operations just described to take place and to cause the counting switch CS in the call controller to advance one step.

Since the digit 4 is stored in the storing switch or register RA, four cycles of relay operations take place and counting switch CS takes four steps at which time wiper 88'1 encounters the grounded conductor No. 4 included in cable 898 said ground extending by way of wiper 914 of the sending control switch S, wiper 934 of the first storing switch RA in engagement with its fourth bank contact terminating No. 4 conductor included in cable 898, through the fourth bank contact engaged by wiper 881 of the counting switch CS and through the winding of slow to release relay 868 to grounded battery for energizing the latter relay. Relay 888, upon energizing, at armature 861 closes a self-restoring circuit for the counting switch CS; at armature 862 completes a locking circuit for itself from armature 851 and at armature 863 completes a circuit for energizing relay 8!8. Relay 818, upon energizing, at armature 811 connects ground at armature 111 to the negative conductor 252 by way of conductors 183 and 2'18 at armature 8!: prepares a circuit for connecting negative battery through the winding of marginal relay 838 to the positive line conductor 258 by way of conductors 185, '184 and 286 when relay 828 is later on energized; at armature 813 disconnects ground to prevent the premature energization of motor magnet 885 and relay 858; at armature 814 prepares a locking circuit for relay 828; at armature 815 disconnects ground from conductor 193 to open the circuit extending through the lower winding of relay 148; at armature 816 prepares a locking circuit for itself and at armature 811 opens a point in the restoring circuit for the sending control switch S.

Relay 828 reenergizes when relay 848 deenergizes and at armature 824 connects negative battery through the winding of relay 838 to conductor 258 to cause energization of relay 328 in the group selector through its second step to start the trunk finding cycle of operations of the first group selector. The circuit for energizing relay 328 in the group selector in series with relay 838 in the call controller may be traced as follows: from ground by way of off normal springs 3E5, which close on the first step of the wipers of the selector, by way of the lower winding of two-step relay 328 through the normally closed springs controlled by armature 334, conductor 258, wiper 2'56, conductor 288, armature 812 and. its working contact, conductor 184, armature 1'12, conductor 1'85, armature 824, and through the winding of relay 838 to battery. The closure of armatures 821 and 822 by operation of relay 828 is ineffective at this time because armature 813 is operated. At armature 823 relay 828 completes a locking circuit for itself from grounded armature 814.

A circuit for restoring the counting switch CS to normal may be traced as follows: from ground by way of the multiple contacts engaged by wiper 886, armature 861, interrupter springs 884, through the winding of magnet 885 to grounded battery. Motor magnet 885 energizes and deenergizes in the manner of a buzzer to advance the wipers of the counting switch until wiper 886 no longer encounters a grounded bank contact at which time wiper 886 will come into engagement with its normal position bank contact. When the counting switch wiper reaches the position shown in the drawings, or its normal position, the circuit through the winding of slow to release relay 858 is opened with the result that this relay deenergizes after an interval. At armature 851 relay 858 opens the locking circuit to relay 868 which deenergizes after an interval, and at armature 852 opens the circuit extending to motor magnet 918 of the sending control switch X; Motor magnet 9|!) deenergizes and steps the wipers 9l3 to 9l5, inclusive, one step into engagement with their second bank contacts in order to control the retransmission of the second digit stored in the second register RB. Relay 860, being slow to release, deenergizes after an interval and at armature 8M opens a point in the previously traced restoring circuit for the counting switch CS; at armature 832 opens a point in its own locking circuit, and at armature 863 opens the original energizing circuit of relay 8m, which latter relay is held energized by way of armature BIG and armature 332 of relay 839 is still in energized position. The trunk finding cycle will normally be completed by the time relay 8% releases and is indicated by relay 33B being in its deenergized position. At this time sending control switch X will be in second position and relay "82B cannot reoperate until the third digit is being rupting circuit until wiper 365 or wiper 3 53 engages a grounded group contact indicating the beginning of a group oftrunks. This grounded bank contact holds the motor magnet 338 in energized position and shunts the high resistance winding of relay 3), thereby causing a relay cycle operation in the controller with the result that battery will be momentarily removed from the negative talking conductor 252. This disconnection of battery from conductor 252 causes the deenergizatio-n of line relay 358 which in turn causes the deenergization of the motor magnet 338, thereby stepping the wipers of the selector to the first contact in the group. After a short interval line relay 3H] is reenergized by the controller in its cycle operation reconnecting battery to negative trunk conductor 252. This reenergizes line relay 313, thereby completing a circuit for operating motor magnet 338 which interrupts itself in the same manner to advance the wipers step by step until wiper 345 or wiper 346 again encounters a grounded group bank contact indieating a succeeding group of trunks. This group selecting cycle of operations continues in this manner until the called group is reached, at which time the controller connects negative battery to the positive conductor 253 to operate twostep relay 320 in its second step. In this case, since the first digit dialled is 4 the wipers of the selector are operated through four cycles of group selecting operations with the wipers resting on the last trunk of the third group and at this time negative battery is connected to conductor 258 to energize relay 323 in its second step to start the trunk finding operation.

Relay 320, upon energizing, through'its second --step, at armature 322 connects ground at armature 3| I through the lower winding of trunk test relay 338 to the test wipers 343 and 344; at armature 323 opens the circuit extending through the upper winding of line relay 310; at armature 325 completes a self interrupting circuit by way of interrupter springs 339 and armature 333 to the motor magnet 338; and at armature 326 connects the group wipers 345 and 346 by way of armatum-333 to the winding of the motor magnet 338. :Motor magnet 338 intermittently operates and advances the wipers of the selector step by-step sin search-ofanidletrunk. As soon as test wiper 343 encounters an idle trunk in this group, indicated by presence of negative battery on the engaged test bank contact, relay 333 energizes over the following circuit: from ground by way of armature 3! I, armature 322, through the lower winding of test relay 330, test wiper 333 in engagement with the bank contact terminating the idle trunk in this group, conductor 356, and through the upper winding of the two-step relay and test relay in the second selector, corresponding to relays 32B and 336 in'the first group selector. Relay 330 at armature 33l connects the negative talking conductor 252 by way of wiper 344 to negative talking conductor 352 extending to the second selector, at armature 332 discon" nects the upper winding of two-step relay 320 and connects the control lead 256 by way of wiper'343 to control lead 256 thereby completing a circuit for operating the two-step relay in the second group selector to operate its armature corresponding to armature 324 in its first step; at armature 333 opens the circuit tomotor magnet 338 to stop the wipers of the selector on the idle trunk; and at armature 334 disconnects the lower winding of two-step relay 320 from conductor 258 thereby opening the circuit to relay 838 in the call controller and connects positive talking conductor 253 by way of wiper 341 to conductor 358.

It will be remembered that the second group selector is identical to the first group selector and therefore negative talking conductor 352 is connected to grounded battery through both windings of the line relay in the second selector while the positive talking conductor 358 is open since the off normal springs in the second group selector, similar to springs Sit and 316 are not yet operated. Ground on control conductor 256 extending from armature H8 in the call controller operates the two-step relay corresponding to relay 326 in the second selector in its first step to open the second selector restoring circuit.

In the call controller relay B38 deenergizes in response to the operation of test relay 339 in the first-selector and at armature 832 opens the locking circuit to relay 8N3. Relay 3H) deenergizes in case relay 356i is deenergized at this time. In response to the deenergization of relay am said relay at armatures 8H and 8E2 connects negative battery and ground to conductors 352 and 358 by way of wipers 3M and 3d? of the first selector. The line relay in the second selector is energized in series with relay 838 in the call controller. At armature 8l3 relay 8m again energizes relay 1 850 over the first contact and Wiper 388 and again at armature 8l3 energizes the motor magnet 885 of the counting switch CS. At armature 8 l4 relay 8H) opens the locking circuit of relay 820, but relay 826 is held energized over armatures 84! and 813, conductor 853, wiper M5, in engagement with its second bank contact, oiT normal springs 333 to ground in case the third digit has been dialled; and at armature 8E5 reconnects ground to conductor 193 to again energize relay M0 to maintain the slow release arrangement in its operated posit-ion. Relay 859 again energizes and at armature 852 again energizes motor magnet Bill preparatory to stepping the wipers of the sending control switch X.

The energization of the line relay in the second selector causes the operation of the motor magnet therein to step the wipers of the second selector into engagement with the first grounded group bank contact at which time the high resistance winding of the line relay is short circuited to cause the operation of relay 838 in a manner similar to that previously described. Relay 838, upon energizing, causes relay 848 to energize and this latter relay in turn causes the deenergization of relay 828. Relay 828, upon deenergizing, causes the counting switch CS to take one step. As soon as wiper 888 engages the grounded multiple bank contacts maintain relay 858 energized. At armature 824 relay 828 opens the circuit to relay 838 and to the line relay in the second selector. The line relay in the second selector deenergizes and causes the motor magnet therein to advance the wipers into engagement with the bank contacts terminating the first trunk in the first group. In the call controller relays 838 and 848 again deenergize and the deenergization of relay 848 again causes the reenergization of relay 828. At armature 824 relay 828 again completes the circuit for energizing the line relay of the second selector in series with relay 838. The line relay, upon energizing, causes the motor magnet to step the wipers over the bank contacts in the first group to the second group of trunks at which time the high resistance winding of the line relay is shorted when the next group bank contact is encountered to cause the energization of relay 838 as previously described. In the same manner as previously described relays 838 and 848 energizerelay 628 deenergizes to step the counting switch CS and to deenergize the line relay of the second selector and relays 838 and 848. This group finding cycle of operations continues until wiper 881 of the counting switch CS encounters the conductor grounded by the second storing switch RB, in this case conductor 5, since the digit 5 is stored in switch RB. At this time the line relay in the second selector energizes and steps the wipers into engagement With the first trunk in the fifth group to start the trunk finding operation. Relays 868 and 818 again energize as previously described and relay 868 restores the counting switch CS. Relay 818, upon energizing, locks the relay 628 energized and reverses the batery connection to the second selector to energize the two-step relay therein in series with relay 838 in a manner similar to that described for the first selector. In a similar manner the two-step relay in the second selector causes the wipers to be automatically stepped in search of an idle trunk in the group and when such trunk is encountered the test relay therein, similar to test relay 338, energizes and connects the call controller to conductors 362, 386 and 368 terminating in the connector shown in Fig. 5.

The energization of the test relay in the second selector opens the circuit to relay 838 in the call controller with the result that relay 838 deenergizes. When the counting switch CS reaches its normal position relay 358 deenergizes to open the locking circuit of relay 868 at armature 851 and at armature 852 opens the circuit to motor magnet 918 to cause the motor magnet to deenergize and step the wipers 913 to 915 of the sending control switch X into engagement with their bank contacts. After an interval relay 868 deenergizes and opens the circuit to relay 818 at armature 863. Relay 818 deenergizes when both relays 868 and 838 are deenergized, it being remembered that relay 838 deenergizes in response to the selector switching through on the idle trunk.

At armatures 811 and 812 relay 818 reconnects battery and ground to conductors 252 and 258 which are noW connected by way of the selector wipers to conductors 362 and 368. At armature 813 relay 818 reenergizes relay 858 by way of Wiper 886 and reenergizes motor magnet 885 by way of armature 822. At armature 814 relay 818 opens the locking circuit to relay 828 but this relay is maintained energized from ground extending by way of off normal springs 963, wiper 915, conductor 853, and armatures 813 and 841. At armature 815 relay 818 reconnects ground to reenergize relay 148 to restart the timing relay arrangement. Relay 858, upon reenergizing, at armature 852 against reenergizes motor magnet 918 preparatory to stepping the wipers of the sending control switch X.

A circuit for energizing the line relay 418 of the connector in Fig. 5 may now be traced as follows: from ground through the lower high resistance winding, through the upper low resistance wind ing of relay 418, armatures 441 and 451, conductor 362, through the bank contact and wiper of the second group selector to conductor 352, bank contact and wiper 341 of the first group selector in Fig. 4, working contact and armature 331, conductor 252, wiper 211, conductor 281, armature 811 and resting contact, conductor 184, armature 112, conductor 185, armature 824 and through the winding of marginal relay 838 to grounded battery. Due to the high resistance winding of line relay 418 relay 838 is not energized in series therewith. Release relay 468 in the connector is energized over the control lead as follows: ground by Way of armature 118, armature 151, conductor 385, wipers 215, conductor 255, armature 332 and working contact, wiper 343, conductor 356, through the wiper and bank contact of the second selector to conductor 366, through normally closed off normal springs 461, and through the winding of relay 416 to battery. At armature 461 relay 468 prepares a locking circuit for relay 458; at armature 462 prepares a circuit for change-over relay 438; at armature 463 prepares the locking circuit for test relay 448; at armature 464 locks up to grounded control conductor 366 independent of off normal springs 461; and at armature 465 prepares a point in the ringing circuit. Line relay 418, upon energizing, at armature 411 completes a circuit for energizing the motor magnet 415; and at armature 412 prepares a self interrupting circuit for motor magnet 415 anda point in the circuit for shunting the high resistance Winding of line relay 410. The circuit for energizing motor magnet 415 may be traced as follows: from the grounded group bank contact normally engaged by wiper 415, armature 411, resting contact and armature 425 and through the Winding of motor magnet 415 to grounded battery. Motor magnet 415 energizes and positions its pawl preparatory to stepping the Wipers of the connector and closes its interrupter springs 416 to shunt the lower high resistance winding of line relay 418 as follows: from ground by Way of armature 412, interrupter springs 416 and their working contacts and thence through the lower winding of line relay 418 to ground.

Relay 838 in the call controller energizes in response to the change in resistance over lead 362 when the high resistance winding of line relay 418 is shunted. At armature 831 relay 838 again completes the circuit for energizing relay 848 and the latter relay at 841 opens the circuit of relay 828 which thereupon deenergizes. At armature 822 relay 828 opens the circuit to motor magnet 885 of the counting switch CS to deenergize such magnet to step the Wipers of the counting switch into engagement with their first bank contacts; 

